1. Field of the Invention
The present invention relates to an ink supply mechanism which supplies ink from an ink container for reservoiring or storing ink to an ink jet recording unit, an ink jet cartridge provided with such a mechanism, and an ink jet recording apparatus provided with such a mechanism.
2. Related Background Art
A recording apparatus having the functions of a printer, a copying machine, a facsimile apparatus, and the like or a recording apparatus which is used as an output equipment for a complex machine or a work station, which includes a computer, a word processor, and the like, are structured to record an image (including characters, marks, and the like) on a recording material (recording medium) such as a sheet or a thin plastic sheet (OHP and others) in accordance with image information. The foregoing recording apparatuses can be divided into such types as ink jet, wire dot, thermo-sensitive, and laser beam, among others types by the recording method to be employed as recording means.
Of these types, the ink jet type (ink jet recording apparatus) is to record by discharging ink onto a recording material from recording means (a recording head). This type enables its recording means to be fabricated compactly, a highly precise image to be recorded at a high speed, and an ordinary sheet to be used for recording without any particular treatment. This type has further advantages such as an inexpensive running cost, lesser noises brought about by a non-impact method, and the ease with which to record a color image using a variety of color inks.
Particularly, for the recording means (recording head) of the ink jet method which utilizes thermal energy for discharging ink, it is easy to fabricate the head having a highly densified arrangement of liquid passages (discharging port arrangement) by forming electrothermal transducers, electrodes, liquid passage walls, a ceiling plate, and others in the form of a thin film on a base board through the semiconductor fabrication processes such as etching, deposition, and sputtering, hence making it possible to make the apparatus more compactly. Also, by utilizing the advantages of the IC technologies and the micro-processing techniques, it becomes easier to elongate the recording means or enable it to provide more area (to be more two-dimensional), hence enabling an easier implementation of a fully multiple arrangement and higher densified assembling of the recording means.
Generally, the above-mentioned recording means for an ink jet recording apparatus comprises an ink discharging unit capable of generating fine ink droplets, an ink supply unit to guide ink to the ink discharging unit, and an ink tank unit which contains ink. Also, the ink jet recording apparatus is generally provided with a recovery mechanism for eliminating the defective discharging of the recording means. The recovery amount (the discharging ink amount used for the recovery process) is usually set at a value of the volume of a part from the discharging ports to the filter for removing dust particles and air bubbles in the ink, which is located on the end of the ink tank side of the ink supply unit, +.alpha..
However, if the recording means is designed in accordance with the above specification, the volume between the discharging ports and the filter inevitably becomes great when the area of the filter is made large in order to reduce the flow resistance for the intended high-speed ink discharging. As a result, the amount of discharging ink used for recovery process becomes great, hence creating a problem that the amount of ink used for the purpose other than recording is remarkably increased.
As in the conventional example described above, the greater volume between the discharging ports and filter brings about the greater amount of ink used for the recovery process. Thus, the following drawbacks are encountered:
Firstly, since there is no compatibility in the recovery amount between an ordinary recording head and a high-speed type recording head, it becomes impossible to use a high-speed type recording head for the ordinary recording apparatus because of the flow resistance created by the filter which results in the insufficient ink supply.
Secondly, as the recovery amount is greater in the high-speed type recording head than the ordinary recording head, the amount of ink used for the purpose other than recording becomes greater, thus wasting more ink. Accordingly, the ink usage efficiency is inevitably lowered.